<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button>点击</button>
    <script>
        var that;
        class Star{
            constructor(uname,age){
                that = this;
                this.uname=uname;
                this.age=age;
                this.button = document.querySelector('button');
                this.button.onclick=this.sing;
            }
            sing(){
                console.log(that.uname);
            }
        }

        var ldh = new Star('刘德华',18);
        //ldh.sing();
    </script>
</body>
</html>